libstdc++/12048

[Loren James Rittle]

> This bug is about cin.unget() no longer working. 

[...]
> Solution 3) doesn't quite meet the requirements of DR 49, but only in
> a rather obscure corner case which I don't expect to be present in
> any real world code [1]. This is very simple to implement.

> Any thoughts?

Yes, thank you for this analysis.  Please consider doing 3, if easy
for you to do ASAP.  Please consider adding an XFAIL test case for the
condition you think must be done according to DR 49.  You have my
pre-approval to do 3.

Doing 1 is not acceptable IMHO since we know it breaks published real
world code.

Regards,
Loren